As is known, two structural procedures are at present used to produce the matched prefabricated blocks.
The first known structural procedure is carried out (see FIG. 1) by employing a special formwork CF which is used to construct one block at a time, using a fixed metal head TM to cast the blocks one after the other, having a patterned surface SM to produce the coupling surfaces of the blocks; the previous, already prefabricated block is used as a counter-caisson. Co designates a previous block which has already been cast and cured, and which is distant from the head TM by an amount equal to the length of the blocks; CX designates the subsequent block under construction, delimited by the block Co and by the surface SM. When the block Cx has been cast, and when the concrete of the latter has cured and has reached the requisite strength, the block Co is removed to the site provided for storage, while the block Cx is displaced to where the block Co formerly was, in a manner such as to be used for the casting of the subsequent block, and so on. Because of the necessity of allowing the casting to cure for at least about a day, the rate of progress is only one block per day. Furthermore, it is necessary to resort to the arduous correction of the blocks, since inevitable deformation of the formwork takes place during casting, so that each individual block always exhibits certain deviations from the theoretically envisaged dimensions; correction is carried out by imparting to the subsequent block a deformation such as to produce a complementary error which cancels the error in the previous block. This correction of the blocks is very arduous and unreliable.
The second known structural procedure envisages (see FIG. 2) the use of a prefabrication bed LF where the individual blocks C1, C2 . . . CN are cast one after the other by means of a mobile formwork which is caused to slide in the direction fC on suitable rollers formed in the bed LF. In this case, correction of the blocks is not necessary, but production is still at the rate of a single block per day, and the apparatus is very cumbersome.